The conventional fluxgate magnetometer depends for its operation upon the rapid AC magnetization of a pair of high permeability cores. Each core carries a primary winding and a secondary winding, one being disposed inside the other. Upon the flow of AC current through the primary windings, the cores are magnetized. The fluctuating magnetization induces currents in the secondary windings. If a DC external field (i.e. the signal field) is present, the magnetization of the core is increased by the external field when the AC magnetic field is in the same direction as the DC field and is decreased when the AC magnetic field in the opposite direction. By employing two cores and arranging their AC fields to be 180.degree. out of phase, the signal obtained from the connected secondary windings is doubled for a DC external field of constant intensity.
Fluxgate magnetometers are commonly employed for the detection and measurement of weak magnetic fields. Because of their sensitivity fluxgate magnetometers are useful for detecting buried or sunken objects whose presence affects the local magnetic field. Because of their directional properties, fluxgate magnetometers have been employed as magnetic compasses.
A major drawback of conventional fluxgate magnetometers is that their response to magnetic field strength is non-linear because of the inherent characteristics of the core material. Consequently, magnetic field strength signals obtained from the conventional fluxgate magnetometer require sophisticated processing to assure the accuracy of measurement.